mlib_ImageStdDev (3MLIB)

Name

mlib_ImageStdDev - image standard deviation

Synopsis

cc [ flag... ] file... –lmlib [ library... ]
#include <mlib.h>

mlib_status mlib_ImageStdDev(mlib_d64 *sdev, const mlib_image *img,
     const mlib_d64 *mean);

Description

The mlib_ImageStdDev() function computes the standard deviation for each channel in the source image.

It uses the following equation:

              1     w-1 h-1
sdev[i] = { ----- * SUM SUM (img[x][y][i] - mean[i])**2 }**0.5
             w*h    x=0 y=0

where, in the case of mean == NULL,

            1     w-1 h-1
mean[i] = ----- * SUM SUM img[x][y][i]
           w*h    x=0 y=0

Parameters

The function takes the following arguments:

sdev

Pointer to standard deviation array, whose size is the number of channels in the source image. sdev[i] contains the standard deviation of channel i.

img

Pointer to input image.

mean

Pointer to pre-computed mean array for each channel. (If NULL, it will be computed.) mean[i] contains the mean of channel i.

Return Values

The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE Interface Stability Committed MT-Level MT-Safe

See also

mlib_ImageMean(3MLIB), mlib_ImageMean_Fp(3MLIB), mlib_ImageStdDev_Fp(3MLIB), attributes(5)